These false-color SEM images reveal microscopic flower structures created by manipulating a chemical gradient to control crystalline self-assembly. (Image courtesy of Wim L. Noorduin.)
Beautiful “flowers” self-assemble in a beaker
"Spring is like a perhaps hand," wrote the poet E. E. Cummings: "carefully / moving a perhaps / fraction of flower here placing / an inch of air there… / without breaking anything."
With the hand of nature trained on a beaker of chemical fluid, the most delicate flower structures have been formed in a Harvard laboratory—and not at the scale of inches, but microns.
These minuscule sculptures, curved and delicate, don’t resemble the cubic or jagged forms normally associated with crystals, though that’s what they are. Rather, fields of carnations and marigolds seem to bloom from the surface of a submerged glass slide, assembling themselves a molecule at a time.
By simply manipulating chemical gradients in a beaker of fluid, Wim L. Noorduin, a postdoctoral fellow at the Harvard School of Engineering and Applied Sciences (SEAS) and lead author of a paper appearing on the cover of the May 17 issue of Science, has found that he can control the growth behavior of these crystals to create precisely tailored structures.
"For at least 200 years, people have been intrigued by how complex shapes could have evolved in nature. This work helps to demonstrate what’s possible just through environmental, chemical changes," says Noorduin.